In the art of primary fuel cells, the power output of fuel cells is determined in large part by the energetic nature and/or character of the fuel elements that are selected and used. In the selection of the fuel elements to be used in fuel cells, great care is used to select and put to use those combinations of elements which are such that the chemical reactions within their related fuel cells is predeterminable, manageable and safe, and which is both effective and efficient to generate desired electric power.
In practice, as the power output requirements of fuel cells increases, the numbers of suitable fuel and combinations of fuel markedly decreases. This is due to the fact that increases in the power output of cells requires the selection and use of more energetic fuel elements and attending or corresponding increases in chemical activity, coupled with the fact that as the energetic characteristics of elements, suitable for use in fuel cells, increases, their chemical stability and suitability for use in fuel cells markedly diminishes and their physical or structural nature and/or character, as regards their suitability for use in fuel cells, diminishes.
In accordance with the foregoing, while the prior art has found little difficulty in the development and provision of primary fuel cells having low to moderate power output, the development and provision of fuel cells having great or high power output has been notably limited. As a general rule, it can be said that as the power output of fuel cells is increased, the latitude of the selection of fuel elements that can be used and the latitude of the design of cell structures suitable for the handling and use of those fuel elements decreases at a notable rate and practical limits are soon reached. In accordance with the teachings of the prior art, the above referred to practical limits have been reached without having put those elements which are known to be the most energetic elements to practical use.
In determining what elements are or might be most energetic for use in primary fuel cells, the mean electrical potential of the elements, when fully oxidized, is looked to. The higher that potential, the more energetic the element would be, if and when put to effective use in a primary fuel cell.
In furtherance of the above, the mean electrical potential of an element is generally expressed in terms of watt hours per kilogram of the element. The watt hour per kilograms is determined by and/or expressed in the formula ##EQU1## wherein E.degree. of the nominator is the mean potential of the element, V of the nominator is the mean valence of the element, and the denominator A is the mean atomic weight of the element. The watt hours per kilogram determined by the foregoing formula is expressed by the voltage output attainable when the element is fully oxidized.
In accordance with the above, it will be apparent and it is readily determinable that the lower the atomic weight (the denominator A) and the higher the mean potential (E) and valence (V) of an element, the more energetic it will be in a primary fuel cell, if its use in such a cell is not otherwise limited or prohibited by one or more of its other characteristics.
In furtherance of the above, it will be apparent that the more energetic elements can be expected to be and are in fact found in those elements having low atomic weight.
Referring to the periodic table of elements, it is apparent that the energetic elements are in period 2. Most notable in the period 2 elements is the element boron (B), the atomic weight of which is 10.82. In accordance with the above noted formula, boron is potentially a very energetic or high powered element. The most notable factors which make boron unsuitable for use as a fuel in primary fuel cells are the fact that it is an extremely poor conductor of electricity with a resistance of 1.8.times.10.sup.12 micro ohms centimeters and is a solid element which is not sufficiently strong and stable to lend itself to being effectively handled, worked with and used in most of those fuel cell structures that have been provided by the prior art.
As a result of the high electrical resistance of boron and due to its physical characteristics, the prior art has apparently and is understood and believed to have determined that while boron has certain characteristics which indicate that it might be an effective highly energetic fuel element for use in fuel cells, it is rendered unsuitable for such use due to its exceedingly high electrical resistance.